Hello,
VLANs are not required for LAGs to function properly. Once you configure the LAG members you can configure the LAG as a trunk port with multiple VLANs, and access port with just one, or even a routed port with an IP address on it.
As long as both sides of the LAG are configured the same way there won't be an issue. Since these switches are Layer 2 only, they don't even do any kind of routing, so your outside IT may have meant a layer 2 loop, which will happen with multiple connections between the same switches. But when you configure them as a LAG is treats those links as the same connection, so there is no layer 2 loop either.
Hope that helps,
Christopher Ebert - Advanced Network Support Engineer
Cisco Small Business Support Center
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