If the 'Upload Contents' is grayed out when you're trying to create a new Dataset, it's possible that you've reached the limit for the number of Datasets per project allowed by your company's deployment of Domino. By default you can create a maximum of five Datasets per project.
If you are setting up a pipeline that requires more than five Datasets, you may wish to consider using separate projects for each logical task that import Datasets from the project that precedes them in the pipeline.
Alternatively, it is also possible for an Admin for your deployment to increase the value for the setting com.cerebro.domino.dataset.quota.maxDatasetsPerProject from the Central Configuration to increase this limit. Note that they would need to restart the services from the Central Configuration UI for the change to take effect
If you still have questions, please reach out to Domino Support at email@example.com.