in element x you can't yet manage spaces. It's silly but it's a relatively new app and and development goes slowly for some reason. you can create the space in element web though, probably element desktop too because they are the same thing.

about the difficulty of registration. you could recommend an instance to them, so they don't need to choose themselves if they don't want to. I recommend one that has set up single signon and element call, and is medium sized (so that it is somewhat prepared for spam waves). https://tchncs.de/en/matrix/ is like that.
what would be even better is if it was using tuwunel instead of synapse, because the former is the more efficient matrix server software, but the other is good enough too.

if you want to put in some more effort, you can have some insight into matrix servers with this tool: https://federationtester.mtrnord.blog/?serverName=tchncs.de

• overview tab shows at top the server software and its version. synapse is official but very resource heavy for the operator, tuwunel is more efficient
• well-known tab can indicate element call support by having defined org.matrix.msc4143.rtc_foci with livekit. I can't believe there is no easier way to check this!
• single signon is supported when the element client's login page for this server allows signing in with external accounts, like github, google, tchncs.de account, etc.

and you can find a list of public servers to check here: https://servers.joinmatrix.org/