By far the easiest option regarding setup is the use of an online service that provides PlanarAlly to you and your players.
At this point in time I do not have the resources to publicly host a PlanarAlly server, but this might be something I would like to add further down the road.
These services are not operated by me and thus I cannot guarantee that the software has not been altered with malicious intent.
If you host or know someone who hosts PA publicly, feel free to let me know!
Dice.Quest (Previously dndbox.com) v2022.1.0 is hosted in Switzerland/Europe and hosts a number of open source projects including PlanarAlly. Support is offerred on reddit.
10leej.com v2022.2.2 hosted in Atlanta, Georgia/USA support provided by 10leej use contact information found on the website frontpage for support.