The version that you download automatically depends on the release version that you have selected. Most users will have the “normal” release version. The “pre-release” version is for those who are providing support or testing.
In PT8 the current “normal” version as of today 2020/1/3 should be 8.0.100.84 and this should be available on the server. The “pre-release” version is 8.0.100.87 and is not available on the server.
You can change the version that you receive in PT8 by holding Shift while clicking on the Help menu. Then go to Advanced > Release Stage