You could create a group named opssl
# groupadd opssl
Now you can give access to that group:
# chgrp opssl /dir/folder1
# chgrp opssl /dir/folder2
# chmod g+w /dir/folder1
# chmod g+w /dir/folder2
# chmod o-rwx /dir/folder1
# chmod o-rwx /dir/folder2
Fist two commands set group ownership, the second pair gives the group write permission, and the third group removes access to anyone but owner and group.
Then create users within this group:
# useradd --gid opssl user1
# useradd --gid opssl user2
NOTE: this will give them access to those directories. Besides that, these users are like any other user you create there.