Hi @ネパリ サンデャ,
For the first issue, you could refer to following steps in the article to fixhttps://switch2sharepoint.wordpress.com/2021/07/19/central-administration-prompting-for-creds-continuously/
When you are stuck in sharepoint product configuration wizard, it usually caused by the hardware and software environment doesn't support SharePoint 2016. You need to use One of the following server operating systems:
- Windows Server 2012 R2 Standard or Datacenter
- Windows Server 2016 Standard or Datacenter
- Windows Server 2019 Standard or Datacenter
Here is the document for reference
https://learn.microsoft.com/en-us/sharepoint/install/hardware-and-software-requirements
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