"Location Access Error" when opening project
If you receive a "Location Access Error" stating the file is not writable when trying to open a Scrivener project, either the project itself or one of its parent folders is set as read-only for your Windows account. Scrivener must be able to save continually as you click through the project, not only your text, but the project's settings, binder structure, interface state and more, so it cannot open a project in read-only mode.
Scrivener's automatic backups are saved as zipped archives by default. Transferring a project via email also requires zipping the project to send it and then extracting it once received.
Although Windows allows you to double-click a zipped folder and view its contents, zipped folders are read-only. You'll need to extract a copy of the project from the archive before you can open it in Scrivener. To do this, either right-click the zipped folder and choose "Extract All" or navigate into the zipped archive and then drag out the .scriv folder to the location you want to save the project. You can then open the extracted project in Scrivener as normal.
A project folder may get marked read-only when transferred from another drive or after being copied or downloaded from a cloud storage service. A lock icon appearing on the files within the project folder indicates that your Windows account does not have write permissions to the files. If you have read and write access to the location the project is saved--e.g. if the project is saved in your user Documents, and you can open and save other files in Documents--check the status of the project folder itself by right-clicking the .scriv folder and selecting "Properties".
Under the "Security" tab, select your Windows user account or the group it belongs to and ensure that it has read and write permissions. You will likely need to provide an administrator name and password to change this if the account does not have the needed permissions.
If the security permissions appear correct, switch to the "General" tab and deselect "Read only" in the Attributes section. Click OK, then in the dialog that pops up, select "Apply changes to this folder, subfolders and files" and click OK. You should then be able to open the file normally in Scrivener, and Scrivener will reset the read-only flags on specific files as needed.