I have been trying for two hours to migrate a WordPress website using Remote from Server. My FTP credentials work when I use them in Filezilla, however, I keep getting a message: "Could not login with specified FTP details". These details are correct. I see you have fixed this issue for others when you log in to their accounts yourself, however, can you please post how you fixed it for them? The documentation is not clear on Siteground or here on how to properly do this and what the proper entries should be based on the hosting company you are moving from. Thank you in advance for any support you can provide.
Is your domain already pointing to the new server ?
Your domain needs to be pointing to the old server and you need to enter the FTP details of the old server from where you need to import the installation.