We cannot activate Personal License in 5.4.0b10 online.

How we can reproduce it using the example you attached
0. Disable all Unity Licenses you have (pro or personal).
1. Install and Open Unity 5.4.0b10.
2. Login and you'll get to License Management page, there only 1 option: Unity Professional Edition license. Personal is disabled.

Actual result: Both Pro and Personal licenses must be active and Personal license can be activated.

As workaround you may:
1. Install 5.3.x or earlier Unity.
2. Activate Personal License there (online or manually).
3. Run 5.4.0b10.