Alternatively, you can create new users from the command line.
This can be done as follows:

If synapse was installed via pip, activate the virtualenv as follows (if Synapse was installed via a prebuilt package, register_new_matrix_user should already be on the search path):

cd ~/synapse
source env/bin/activate
synctl start # if not already running
Run the following command:
register_new_matrix_user -c homeserver.yaml
This will prompt you to add details for the new user, and will then connect to the running Synapse to create the new user. For example:

New user localpart: erikj
Password:
Confirm password:
Make admin [no]:
Success!

This process uses a setting registration_shared_secret, which is shared between Synapse itself and the register_new_matrix_user script.
It doesn't matter what it is (a random value is generated by --generate-config), but it should be kept secret, as anyone with knowledge of it can register users, including admin accounts, on your server even if enable_registration is false.

https://element-hq.github.io/synapse/latest/setup/installation.html

I have to set literally everything up again on a new microSD for my Pi because the apt-get repositories no longer support the Raspbian version I'm on. I'm not mad; good for security to update, but I don't have half a day free anytime soon for it.

I don't understand what isn't clear here?

Old I.T. Proverb: Documentation is like sex. Even bad documentation is better than no documentation at all.

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

5 acronyms in this thread; the most compressed thread commented on today has 3 acronyms.

[Thread #905 for this sub, first seen 3rd Aug 2024, 13:15] [FAQ] [Full list] [Contact] [Source code]

this is just because it's webhosted, anything that does anything on the web sucks and is terrible, everything else is actually so much better it's fucking baffling to me.

web 2.0 is dead to me. web 3.0 won't get off of the ground, we need web 2 electric boogaloo

Setting up synapse is particularly painful.