I changed the version to "stable", so there were no downgrade (2.6.0beta7 ->>2.6.0).
rest is simple, (here is steps for anyone who want to migrate)
just install discourse on cloudron,
set a demo subdomain to avoid (down time),
upload backup file, start restoring process.
once restore completed u will logout, signin again with your admin account (The one you use on migrated).
go to cloudron dashboard & change to to the real domain. update it from domain register if you use manual domain.
be sure in discourse dashboard that the notification email domain is OK.
it will take around 1 minute with almost zero down time.
to be sure everything is OK, shut down the old server/vps.