Error: Process 'command 'C:\Program Files\Java\jdk1.8.0_291\bin\java.exe'' finished with non-zero exit value 1

Scan: https://scans.gradle.com/s/nejkwuhiqxpa6

You need to update you're runs in the build.gradle file to run the client / server with these properties while utilizing the official Mojang mappings:

runs {
        client {
            workingDirectory project.file('run')
            property 'mixin.env.remapRefMap', 'true'
            property 'mixin.env.refMapRemappingFile', "${buildDir}/createSrgToMcp/output.srg"
            mods {
                yourmodidhere {
                    source sourceSets.main
                }
            }
        }

        server {
            workingDirectory project.file('run')
            property 'mixin.env.remapRefMap', 'true'
            property 'mixin.env.refMapRemappingFile', "${buildDir}/createSrgToMcp/output.srg"
            mods {
                yourmodidhere {
                    source sourceSets.main
                }
            }
        }
}

Then regenerate your runs with eclipseRuns / ideaRuns etc.

However this will still crash due to a incompatibility with mojmap in the tool Registrate by tterrag which Create relies on.
This incompatibility issue has now been fixed in version MC1.16.5-1.0.4 of Registrate.
Pull request fixing incompatibility issue: tterrag1098/Registrate#29.

I have already made a pull request bumping the registrate version for Create:
#1615.

I hope Create can start making use of the latest version of Registrate soon so that it will be easier for modders to create addons and mod compatibility for Create. In the end it will benefit both parties.

So it will work after the Create Team updates to the newer Version of Registrate?

Yes, pretty much. Unless there are more problems in the pipeline not yet uncovered. But we can't know for sure until this is fixed in the first place.

This should be fixed, I updated Registrate to fix this a while ago.