See the instructions at xrdp_local_session for more information.
For APT-based distributions, put the file at
/etc/apt/sources.list.d/xrdp-local.list and run
apt update.
For RPM-based distributions, put the file at
/etc/yum.repos.d/xrdp-local.repo.
Also grab the
GPG key
and put it at /etc/pki/rpm-gpg/GPG-KEY-xrdp-local.