Information about the shell access part of SDF is at their website ( https://sdf.org/ ). The Join page explains a bit more as well as how to upgrade your membership to a different level.
Basically, you can register for a free shell account. You can opt to pay for lifetime ARPA access ($36 paid once) to get access to developer type programs. The MetaARPA level ($ 36 a year) gives you even more things.
Software that is accessible at certain membership levels can be shown after logging in to your terminal by typing in software and following the on screen directions. You can pipe the command over to grep to learn that git only shows up at the ARPA level. As far as I know, you need to be ARPA or higher to access git. Regardless, you need to be ARPA to access compilers like gcc so you may want to upgrade anyway.
Notably, I am at the ARPA level and I can run the git command without any issues.
What may help in the future is that you have access to the bboard command. There you can post help messages to the HELPDESK board which may receive a faster response.
http://sdf.org/?tutorials/bboard-tutorial -- This explains how to use bboard.