Keep vertical synchronization enabled in the Graphics settings, so the frame rate stays locked to your monitor's refresh rate — disable it only if you are certain of what you are doing. A GPU pushed to 100% utilization runs into its TDP limits and throttles, turning smooth play into a stutter.

After downloading, unpack the archive and drag Medivia Online into the Applications folder: open Finder, click Downloads in the sidebar, then drag the app onto Applications in that same sidebar. The client can only update itself from inside Applications — started from Downloads or the desktop instead, it moves itself into Applications on the first launch and restarts from there.

macOS blocks the first launch of Medivia Online because the app is not signed by an identified developer. To open it anyway:
1. Double-click Medivia Online and dismiss the warning — this first blocked attempt tells macOS you want to run the app.
2. Open System Settings → Privacy & Security, scroll down to the Security section and click Open Anyway next to the message that Medivia Online was blocked, then confirm.
On macOS 14 Sonoma or older you can instead Control-click (or right-click) the app in Finder and choose Open; if the dialog has no Open button, close it and repeat right-click → Open once more. From macOS 15 Sequoia on this shortcut no longer exists, so use System Settings as described above.
Once the app has opened this way a single time, every later launch works like any other app.