Terminal said ‘tar: Error opening archive: Failed to open 'libwebp-0.4.3.tar.gz'…’, when I execute ./build.sh in terminal

[SummerWu]

The following are the details ：

jiehaodeMacBook-Pro:libwebp-build jiehaowu$ ./build.sh
tar: Error opening archive: Failed to open 'libwebp-0.4.3.tar.gz'
./build.sh: line 64: cd: libwebp-0.4.3: No such file or directory
sh: autogen.sh: No such file or directory
./build.sh: line 76: ./config.guess: No such file or directory
./build.sh: line 76: ./configure: No such file or directory
make: *** No targets specified and no makefile found. Stop.
make: *** No rule to make target install'. Stop. cp: /tmp/install.19985.i386/include/webp/*: No such file or directory tar: Error opening archive: Failed to open 'libwebp-0.4.3.tar.gz' ./build.sh: line 64: cd: libwebp-0.4.3: No such file or directory sh: autogen.sh: No such file or directory ./build.sh: line 76: ./config.guess: No such file or directory ./build.sh: line 76: ./configure: No such file or directory make: *** No targets specified and no makefile found. Stop. make: *** No rule to make targetinstall'. Stop.
cp: /tmp/install.19985.x86_64/include/webp/: No such file or directory
tar: Error opening archive: Failed to open 'libwebp-0.4.3.tar.gz'
./build.sh: line 64: cd: libwebp-0.4.3: No such file or directory
sh: autogen.sh: No such file or directory
./build.sh: line 76: ./config.guess: No such file or directory
./build.sh: line 76: ./configure: No such file or directory
make: ** No targets specified and no makefile found. Stop.
make: *** No rule to make target install'. Stop. cp: /tmp/install.19985.armv7/include/webp/*: No such file or directory tar: Error opening archive: Failed to open 'libwebp-0.4.3.tar.gz' ./build.sh: line 64: cd: libwebp-0.4.3: No such file or directory sh: autogen.sh: No such file or directory ./build.sh: line 76: ./config.guess: No such file or directory ./build.sh: line 76: ./configure: No such file or directory make: *** No targets specified and no makefile found. Stop. make: *** No rule to make targetinstall'. Stop.
cp: /tmp/install.19985.armv7s/include/webp/: No such file or directory
tar: Error opening archive: Failed to open 'libwebp-0.4.3.tar.gz'
./build.sh: line 64: cd: libwebp-0.4.3: No such file or directory
sh: autogen.sh: No such file or directory
./build.sh: line 76: ./config.guess: No such file or directory
./build.sh: line 76: ./configure: No such file or directory
make: ** No targets specified and no makefile found. Stop.
make: *** No rule to make target `install'. Stop.
cp: /tmp/install.19985.arm64/include/webp/*: No such file or directory
fatal error: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo: can't open input file: /tmp/install.19985.i386/lib/libwebp.a (No such file or directory)

Excuse me how should solve ？