QB Issue Resolution:

You can download it again so long as you have the license and product key codes usually found on the cd jacket.

Resolution for Issue 'If I have a cd for a 2015 mac update and buy a computer without a cd drive, can I download it again online with the license number?' available: Yes (Solved).
Source: Intuit Community forum.

If I have a cd for a 2015 mac update and buy a computer without a cd drive, can I download it again online with the license number?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for License
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Error Recovery for License [Canada]
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