We inspected your site and it seems like there are few errors.
service worker scripts not present in HTML: Maybe an issue with cache, so can you please check it once by clear all server-side caches(CDN/cache plugins/etc)
For image errors in manifest: Upload proper 192×192(icon) & 512×512 (splash screen) in PWA option panel.
Can you please check it once the above and let us know back?