I work in Debian, and I add "postgres" user to "myuser"'s group that own the folder:

usermod -a -G myuser postgres

then I use chmod for give access to the user of the group, and create the table space folder

chmod 775 /home/myuser

su postgres

mkdir /home/myuser/ . . . /TableSpaceFolder

and finally use the command in "psql"

postgres=# create tablespace ts_name owner role_name location '/home/mysuer/ . . . /TableSapaceFolder';

CREATE TABLESPACE

Work for me.