Multistage sampling method Help

#1
I want to make a multi linear regression analysis of 5 independent variables and 1 dependent variable.

My interest is observing virtual team members and their behavior, the problem I have is that I don't have an specific population.

The only data I could get was the number of companies that have manufacturing activities; and the people I can contact to help me by answering surveys are from purchasing departments

The idea I had was to say I am measuring virtual team members from the purchasing department of manufacturing companies.

I detected 1122 manufacturing companies by simple random sampling I got 145 companies but, I can't go to each of the 145 companies.

Is it possible to randomly select 145 purchasing department people from any of those companies and to justify why I am not observing 145 different companies?

Like for example: simple random sampling on the companies
then strata or clustering the sample size of the companies?