Use the address you want opened
Paste the full page address, including the path. Still adds https:// when the scheme is missing, and the preview shows the exact text that will be stored. Check that line before you download.
A short page address makes a simpler pattern. A very long address, especially at High damage tolerance, can become too dense to encode. If that happens, shorten the path or choose Low or Medium.
Leave the margin alone
The blank frame around the modules is the quiet zone. The specification asks for four modules of margin. Still includes that margin. Cropping it off in a design file makes scanners miss the code.
Give the code a solid light background. A photo, a gradient, or a pattern behind the modules is a common reason a printed code fails.
Pick a tolerance for the surface
Low can recover about 7 percent of damaged modules. Medium can recover about 15 percent. Quartile can recover about 25 percent. High can recover about 30 percent. Medium is the right default for a website address on a screen or a clean print.