Problem:

Failed to copy Payload for STAAD.Pro Connect Edition while installing. Specifically for RCDC
Here's the error.

Solution:

Though error message does not appear on all the machines. However, on some of the machines the error does appear.
The solution remains in deployment of installation image.

This is how to create the Deployment Image:

Open the folder where you have downloaded the STAAD.Pro installation file (say, setup_StaadProx64_22.10.00.153.exe).

1. Copy the path of this installation file.

2. Run this installation file with "/layout" command i.e., 

“Copied Path\setup_StaadProx64_22.10.00.153.exe" /layout

3. The STAAD.Pro Installation Wizard opens. Default "Installation Directory" is C:\Program Files\Bentley\Engineering\STAAD.Pro CONNECT Edition\. It is not recommended to change the default installation directory but the user can choose a different location, if required.

For further information please visit https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/40059/steps-to-create-deployment-image-for-staad-pro-ce