When I try to compile, I have the following questions.

[NeXT1995]

CMake Error at cmake/PICMake.cmake:451 (find_package):
By not providing "FindEigen3.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "Eigen3", but
CMake did not find one.

Could not find a package configuration file provided by "Eigen3" with any
of the following names:

Eigen3Config.cmake
eigen3-config.cmake

Add the installation prefix of "Eigen3" to CMAKE_PREFIX_PATH or set
"Eigen3_DIR" to a directory containing one of the above files. If "Eigen3"
provides a separate development package or SDK, be sure it has been
installed.
Call Stack (most recent call first):
CMakeLists.txt:8 (pi_collect_packages)

[gisnewbird]

try that
$ sudo apt-get install libeigen3-dev ?