URL:phising app.interactiveme.org.uk real/not real threat?

This is not about pop-ups. This question is about wther the site InteractiveMe (https://app.interactiveme.org.uk/profiles/1259/session/new) is safe for my wife to use for contact with her mother who is in a care home. Is this site infected or is it a false positive. Thank you.
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Hello Nick,

You can find answer to your question together with your another post here https://support.avg.com/answers?id=9065p000000PnBh
Please try keep whole conversation in one question/thread to speed up resolution. Thank you.

Every time I try to login to https://app.interactiveme.org.uk/profiles/1259/session/new  I get a threat secured URL:phising but the company say there is no issues with their site.
Is this an error?
Thanks

https://app.interactiveme.org.uk/profiles/1259/session/new
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