My guess would be air in the system. Many clutch master cylinders must be bench bled correctly before installing.
The master clutch cylinder is attached to the clutch pedal. When one depresses the pedal hydraulic fluid is forced from the master cylinder through the hard line to the slave cylinder. The piston in the slave cylinder is driven against the clutch linkage thereby releasing the clutch.
If you allowed the master/reservoir to drain empty while the line was disconnected or installed the master dry, you may have to remove the master and bench bleed it first. Always keep the reservoir full during the process.
Check Clutch master and slave cylinders
The clutch master cylinder is in the engine compartment and the slave cylinder for the hydraulic clutch is inside the manual transmission bellhousing
The clutch pedal assembly has a clutch rod that pushes in on a clutch master cylinder. There is a hydro line that goes from the master cylinder to the slave cylinder.
This is a hydraulic master and slave cylinder clutch, there is no adjustment. Check for a leak in the system, a faulty master or slave cylinder, or wear on the clutch plate.
The clutch is not adjustable. The hydraulic master/slave cylinder assembly self compensates for wear. You have a problem with the clutch of master/slave.
There are two normal causes. The clutch is worn out or there is a leak in the hydraulic clutch slave or master cylinder. To check the clutch, press the clutch slave cylinder down. If the clutch slave cylinder bellows compresses down to the slave cylinder, the clutch is worn out. Check the clutch master cylinder fluid level. if this is low, then the clutch cylinder need to be checked. To check for a hydraulic leak in the clutch slave cylinder, remove the cylinder's bellows and check for any fluid. If fluid is present, rebuild or replace the cylinder and bleed the system. To check the clutch master cylinder, check the back the of clutch master cylinder for leaks. If fluid is present, replace or rebuild clutch master cylinder and bleed the system. In my experience, hydraulic leaks occur at the clutch slave cylinder.
At least the slave cylinder. The clutch master cylinder can be replaced at any time.
It sure sounds like your clutch is worn
The clutch master cylinder is in your engine compartment , the hydraulic clutch slave cylinder is inside your manual transmission bell housing
First you need to find out if your slave cylinder is leaking clutch fliud.check lines to slave cylinder from master clutch cylinder if no leaks most likely master clutch cylinder bad.