There are two ways to sign in to Veloxy, either by using your Salesforce credentials, or by using the Email Address and Password associated with your account.
To sign in to Veloxy, tap on Login using Salesforce button, as shown in the following illustration.

You will be taken to the Salesforce login screen (shown below). If you are NOT using any Custom Domain, you can enter your Salesforce credentials to sign up for Veloxy.

If your company uses Salesforce Custom Domain, tap on Use Custom Domain link (shown in the above illustration), enter the name of the custom domain (shown in the illustration below) and tap Continue.

You will be redirected to your company Salesforce login screen (shown in the illustration below). Enter your Salesforce credentials to sign up for Veloxy.