Direto connecting issue

[joeking22]

Hello guys,

I bought a second hand Direto (2 year old) which I want to connect with Zwift wia my old iMac (2011 model). It all runs properly on my pc but the iMac can't find the Direto via bluetooth. Any ideas how to clear this? I know it's an old computer but the screen is very nice so I'd like to give it a go.
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Thanks in advance