How do I configure an NFS server to accept all mount requests?

Try

/filesystem      *

You might also try reading man exports, which has a set of examples at the bottom from which the above is derived. You may also wish to note that 0.0.0.0/32 means "only the IP address 0.0.0.0". It is possible that you wwanted 0.0.0.0/0, which means "any IP address", instead, but * should do as well.

You should also set permissions with the share:

     /folder-location *(rw,no_root_squash,no_subtree_check)