What type of Visa I should apply for educational internship in a company?

[Mike9]

Hello,

I am a Ph.D. student in Germany. As a part of my study, I should spend 6 months in a British company to complete my thesis research. I am a Non-EU citizen, so I need to get a visa for the UK. I couldn't understand which kind of Visa I have to apply for. I found short-term study visa more relevant to my purpose of travel, but I doubt if I can apply for the short-term study visa.
For the short-term study visa, one of the requirements is as follows: "you must be carrying out the research at a UK higher education provider". The place I must go for the research is not a UK higher education provider but is a company. I have an invitation letter from the company stating that they invite me for a six-month educational internship.
Could you please help me to realize what type of Visa I should apply for?
I really appreciate your guidance.