Windows 10 has two types of startup folders, one for all users and one for each individual user.
There are a number of ways to access the folders. The following are how I tend to access them, but I do it infrequently enough that I usually have to look it up so I’m creating that resource for my easy reference now.
The all users startup folder can be found here:
Each individual user startup folder can be found here (replace [User Name]):
c:\Users[User Name]\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup
Alternatively, I most often use the Run command to open them.
Windows key + R
At the run command prompt
Open the all users folder:
Open the current user folder: