If you just need to play downloaded 4K MKV/MP4 files, use PotPlayer or MPC-HC . They’re free, safe, and updated. If you need actual Blu-ray disc menus (for discs you own), buy a cheap Leawo license or wait for a PowerDVD 23 sale ($39.99 during holidays).
Version 19 sometimes struggles with identifying obscure ISO files or newer disc formats. Cyberlink Powerdvd 19 Ultra Pre-activated