Thanks! Please ensure that you need to use your own personal account for the sandbox to activate As in case of work account authentication and authorization is defined by your IT admin and hence won't allow you to activate/create paid resources (unless you are on approved list) or free sandboxes. Try using your own Microsoft account. Create a new free account if you don't have one yet.
Also, MVA learning is not currently supported here on QnA. You may try asking for help in dedicated forums here:
https://trainingsupport.microsoft.com/en-us/mcp/forum/mcp_exams-mcp_exam-mcp_pearson
https://trainingsupport.microsoft.com/en-us/mcp/forum/mcp_exams-mcp_exam-mcp_crash
--Please don't forget to Accept as answer if the reply is helpful--