I am able to install/run a Windows 98 Second Edition VM on version 15.5.7 with an Ubuntu host with i7-8700K CPU.

Perhaps we can check the CPU feature capabilities of the 11th gen i5 you have. No guarantees that it will work but perhaps masking the host CPU features might let it work.

If you can attach the vmware.log of Windows 98 VM or share the appropriate sections

vmx| I005: hostCPUID
vmx| I005: Host VT-x Capabilities:
I005: FeatureCompat: Capabilities:
I005: FeatureCompat: Requirements: