...

If you share a space, you are essentially creating a website — anyone who has the URL can view the space. Whether or not someone can actually open a form or flow and use it depends on the Visibility property of the form. A form or flow must be Public for anyone to use it. An outside user will be blocked if he attempts to open a non-public form, and may even lose his session credentials with the space. Forms/flows must be deployed to production for them to automatically appear in an application tab menu. If the visibility of a form is restricted to a specific role via the ACL feature, the form/flow will not appear on the space menu unless the logged in user has been assigned that role or they are the designer. 

...

Notice the First and Last Names of the logged in user appear in the upper right corner.
Image Removed
Image Added

Create a New Space

When you create a space,  creates a tab on the space for each of your applications — and also adds Task List, My Account, Shared Items, Home and Login/logout tabs. Refer to the Space Content topic. The application tabs display a list all of all deployed forms/flows in that application; undeployed forms and flows are not included. For testing purposes, forms/flows with a visibility setting of private are added to the space menu if the user is logged in as a designer. A form/flow with a visibility set to public in tenant, cannot be accessed unless the user logs in to the  tenant. If the visibility of a form/flow is restricted to a specific role via the ACL feature, the form/flow and it's associated tab will not appear on the space menu unless the logged in user has been assigned that role or they are the designer. If an application has no forms/flows,  doesn't create a tab for it. 

...

1. Log in as the designer, and then click on Spaces  .
2. Click to create a new space, enter a Space ID. The Space ID must be unique, start with a letter, cannot contain spaces or special characters and cannot exceed 16 characters. Non-ascii characters are not supported in a space id.
3. Enter a Space Name - this name will display in the top right section of the space. The Space Name should not exceed 16 characters but you can type spaces here.
4. Click Create.

Image RemovedImage Added

The new space is added to the list.  
Image Removed
Image Added

The spaces home page lists any spaces that you've already created. On this page, you can:

...

Adding an Anonymous Signup form link

You can add the URL to an anonymous signup form for your tenant. Users can create a user account in your tenant using this published registration URL. The  designer does not have to create the form, the URL shown below accesses the Add User Anonymous Register form included with . When thsi form is submitted, the user receives an activation email which enables the account.  

You must check Anonymous Users in your tenant to take advantage of this feature. Also, there is an invisible control on this form which requires the tenant name. The form will not submit if this field is left blank. Append _data parameter to initialize the control with your tenant name: 

...