Dimensions wont start on Macmini with eGPU?

Hello, i have a macmini 2018 with an external GPU and Mojave 10.14.6.
The e GPU is a Radeon RX Vega 56 8 GB.
Is there a possible workaround to start Dimensions on my hardware?
The open GL version seems to be too old.
But how to update open GL?
When try to start dimensions following error occurs: