arduino Gravity: Digital 1-to-8 I2C Multiplexer

Good evening. I purchased the Gravity: Digital 1-to-8 I2C Multiplexer to use with Arduino Uno R4 WiFi. I loaded the library on Arduino IDE but when I go to load the program it gives me this error: Compilation error: DFRobot_I2CMultiplexer.h: No such file or directory. can you help me because I have already tried to reinstall the library but it doesn't work. thanks for anyone who can help me