Cannot save from SP2019

[unity_one]

When trying to save a form the following error is thrown - Connecting as Site Collection Admin

Microsoft.SharePoint.Client.ServerUnauthorizedAccessException: Access denied. You do not have permission to perform this action or access this resource.
at Microsoft.SharePoint.Client.ClientRequest.ProcessResponseStream(Stream responseStream)
at Microsoft.SharePoint.Client.ClientRequest.ProcessResponse()
at Microsoft.SharePoint.Client.ClientRequest.ExecuteQueryToServer(ChunkStringBuilder sb)
at Microsoft.SharePoint.Client.ClientRequest.ExecuteQuery()
at Microsoft.SharePoint.Client.ClientRuntimeContext.ExecuteQuery()
at Microsoft.SharePoint.Client.ClientContext.ExecuteQuery()
at SuObVeYDfjlEJatGhs.tCnfNSEuN1GIqRxfZ2.<>c__DisplayClass27_0.<SetLayoutAsync>b__0()
at System.Threading.Tasks.Task.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at SuObVeYDfjlEJatGhs.tCnfNSEuN1GIqRxfZ2.<SetLayoutAsync>d__27.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at FormsDesigner.ViewModels.DesignerViewModel.<SaveAsync>d__194.MoveNext()

[AlexZver]

Hello!

Possibly, the site collection is in the read-only mode, please create another site collection and try there.