If you are the PI of an ALMA proposal that got data, you can delegate access to these data during the proprietary period to anyone with an ALMA account (Co-I's or other ALMA users).
To do this, log into the ALMA Science Portal using your ALMA username and password. Then, hover your mouse over your name next to the magnifying glass at the top right of the page. Select "Preferences" from the drop down menu, and when the "Edit Profile" page appears there should be three tabs: "Account info", "Project delegation", "Account linking", and "Demographics". Click Next on the top right to advance to the Project Delegation tab.
Click the "Add delegee" button: a window will pop-up where you can choose one of the projects where you are PI. Select delegation type "DATA". Select a delegee by typing his/her family name, suggestions will be given as you type. Click "Next" until you get to the Confirmation page where you can validate and click "Update". Once this information has been replicated into the database (it may take a few minutes), the delegee will be able to download the proprietary data using the link sent to the PI in the data delivery email notification.
If you already have delegees for your projects and want to add new users but the Add button is grayed out, try clicking the Clear Selections button.
You can remove permissions on the same page, using the "Remove delegee" button. Clicking on any delegee row in the tab, the Remove delegee button becomes enabled. Selection can be cleared with the Clear selection button. Click on the Remove button: a popup asks for confirmation. If you click on Cancel nothing happens. If you click on OK the delegation row disappears from the tab.