You can absolutely stop playback on a specific frame. The timeline has a built-in “scene end” marker that tells the preview exactly where to halt.
If you already have the playhead on the frame you want, open the timeline toolbar, turn off Auto Scene End, and click Scene End = Playhead. That locks the stop point to the current position.
If you prefer doing it directly on the ruler, right-click the timeline and choose Set Scene End Here. That puts the stop point wherever you clicked. Once it is set, the preview will stop automatically as soon as it reaches that frame. You can switch back to automatic behavior at any time by turning Auto Scene End back on.
The program has had a lot of updates over the last couple of days. If you are using an older build, it might help to redownload so everything behaves as described.
If you want even more precise frame control, such as single-frame stepping or numeric time entry, tell me what you need and I can work it into a future update.