There's not really much more to explain which isn't already covered on the DNSViz URI I pasted above. If you hoover over the triangular icons with the exclamation mark, you'll see the actual error messages.
The main error (in the graph pointed out by the big red error from the "net" zone to your domain) is:
No valid RRSIGs made by a key corresponding to a DS RR were found covering the DNSKEY RRset, resulting in no secure entry point (SEP) into the zone.