You can manage & track your card collection and decks once you create an account and login.

Card Set Downloader
This allows you to download an image pack of any set supported by Teletraan I, be it a WotC release or a community set. The download may take a little bit to start, so please give it some time and try not to refresh.

Select the set you'd like to download and options. Images are 300 DPI and use the following measurements: small cards are 63 x 88 mm (744x1039px), standard bots are 88 x 128 mm (1039x1512px) and extra large bots are 144 x 200 mm (1701x2362px).
"Bleed" adds a border to the card that is cut off during professional printing on to cards. It is not typically desired for printing at home or a place like Office Depot.

Additional Downloads
Jihen's Community Pack for OCTGN [Download] Updated Nov 26th 2020
Jihen has created a downloadable pack to add additional sets to OCTGN. Adds OCTGN support for ATP-1 & ATP-2, as well as The Ark's Unicron Raid. To install, simply unzip to your OCTGN Data directory. His GitHub offers additional sets not supported by Teletraan I.

Community Sets
PDFs and ZIPs created by the Card Set Downloader are auto-generated on the fly from Teletraan I's library of card images. Original download links are listed below.
ATP-1 by Alpha Trion Protocols Using v1.3 from Nov 13th, 2020
ATP-2 by Alpha Trion Protocols Using v1 from Nov 26th, 2020
ATP-3 by Alpha Trion Protocols Using v1 from Feb 28th, 2021
Primus Pack 1 by Alpha Trion Protocols Linked set from Nov 4th, 2020. However, Teletraan I uses newer versions from Nov 19th that were only shared in Discord.
Ark 1 by The Ark Using v1 updated Nov 26th, 2020
Unicron Raid by The Ark Using v1 from Nov 26th, 2020
World|Strike by Team Bayformers Using v1.1 from March 19th, 2021
Printing Cards
You primarily have two choices when it comes to printing cards (community set or otherwise). The first, cheapest, and easiest option is to print them on your home printer or at a office supply store like Staples. If you want something more substantial but costs more, you can also get them professionaly on card stock.

At Home & Office Printing
If you want physical copies of the cards right now and quality doesn't matter, print them on your home printer. The easiest option would be to download the cards as a single PDF without bleed. Once all printed, take some scissors and spend some time cutting them out.

If you want something a little nicer but still very affordable, then you can print them at a place like Staples or Office Depot. I personally haven't printed at Staples before, but I have used Office Depot many times and I imagine the setup and outcome is very similar.

First, download the set(s) you want to print as a single PDF without bleed. I like to use their 100lb &Gloss cover premium white& paper. Make sure "Keep Size" is selected, you don't want them to scale this down at all. Once printed and cut out, sleeve the battle cards over an existing card (like Zap or something) it'll look very much like a real card. For the character cards, they're laid out as such that you should be able to glue their pages back-to-back and then cut.

Professional Printing
If you wish to have copies that feel and handle like the real deal, then you'll need to get them professionally printed. Brian Alan a good post on Facebook about this which is quoted below. You can read the full discussion on Facebook thread discussing printing options.

Written by Brian Alan
I just ran some rough numbers on getting two of the larger fan sets printed at MakePlayingCards and here's what I came up with:
-Getting roughly 24 character-sized cards (3.5" x 5") and 164ish to 240ish battle cards/small characters/strat-sized cards (2.5" x 3.5") should be about $60-$75ish, with shipping probably running you about $20 on top of that, possibly more if you're not in the US.
-If someone is charging you $80+ish and you're not getting 150+ cards, you're getting suckered.
-You can bring that cost down significantly by partnering with other local or even local-ish people who may be interested (discount on buying multiples and saving on shipping).
-If you don't mind paying a LITTLE extra, you can also get your small characters and strats with holofoil on one side.
-There's not a cost-effective option right now to have MPC do a holofoil side on 3.5" x 5" cards. I emailed them to check on the cost and it's pretty ridonk ($95 for a deck of 84 regular character-sized cards).
-They don't print Titan-sized cards. I might just recommend ordering two matte (not glossy) 6" x 8" photos and putting them back to back in a sleeve/top loader.
Dave at Energon Hustlers did a fantastic tutorial on how to use MPC that you should definitely consider checking out: