customizing latex table color and adding footnote - latex

Question

Given the following code, I would like to remove the colours and add a third column including *, **, *** to show the grouping of, for example, 2,4 and 7 and... and then in the footnote what each start group mean.
\documentclass{article}
\usepackage{geometry}
\usepackage{xcolor}
\usepackage{tabularray}
\begin{document}
\begin{tblr}{
colspec={l|[white]l},
cell{1}{2}={halign=c},
rows={bg=lightgray},
row{1}={bg=brown!80,fg=white,font=\bfseries},
row{2}={bg=brown!80!black,fg=white},
row{4}={bg=brown!80!black,fg=white},
row{6}={bg=brown!80!green,fg=white},
row{7}={bg=brown!80!black,fg=white},
}
Number & Model \\
\hline[white,wd=1pt]
Model 1 & \(\text{BC\_WS} = \beta _0 + \beta _1\cdot {\text{M\_WS}} + \epsilon\) \\
Model 2 & \(\text{BC\_WS} = \beta _0 + f(\text{M\_WS}) + \epsilon\) \\
Model 3 & \(\text{BC\_WS} = \beta _0 + \beta _1\cdot W\_WS+ \beta _2\cdot \text{\text{W\_Direction}}+ \beta _3\cdot \text{Temperature} + \beta _4\cdot \text{Pressure} + \epsilon\) \\
Model 4 & \(\text{BC\_WS} = \beta _0 + f(\text{M\_WS})+ f(\text{W\_Direction})+ f(\text{Temperature}) + f(\text{Pressure}) + \epsilon\) \\
Model 5 & \(\text{BC\_WS} =\beta _0 + \beta _1\cdot (\text{M\_WS})+ f(\text{W\_Direction})+ f(\text{Temperature}) + f(\text{Pressure}) + \epsilon\) \\
Model 6 & \(\text{BC\_WS} = \beta _0 + \beta _1\cdot M\_U+ \beta _2\cdot \text{M\_V}+ \beta _3\cdot \text{Temperature} + \beta _4\cdot \text{Pressure} + \epsilon\) \\
Model 7 & \(\text{BC\_WS} = \beta _0 + f(M\_U)+ f(\text{M\_V})+ f(\text{Temperature}) + f(\text{Pressure}) + \epsilon\)
\end{tblr}
\end{document}
The output from the code above looks like this:
I tried to remove the, for example, row{2}={bg=brown!80!black,fg=white}, to remove the colouring, but I received the following error:
! Paragraph ended before \environment tblr was complete.
<to be read again>
\par
l.113
I want the output to look like this with footnotes about the stars(header row and first column are aligned centre, the remaining are aligned left):

Answer 1

The error has nothing to do with the row colours, you are missing the amsmath package. Without this package you can't use the \text{...} macro.
\documentclass{article}
\usepackage{geometry}
\usepackage{xcolor}
\usepackage{tabularray}
\usepackage{amsmath}
\UseTblrLibrary{booktabs}
\begin{document}
\noindent\begin{tblr}{
colspec={#{}l|[white]Xc#{}},
hline{1,Z}={wd=1.2pt},
hline{2}={wd=0.4pt},
cell{2-Z}{2}={mode=imath}
}
Number & Model & Type\\
Model 1 & \text{BC\_WS} = \beta _0 + \beta _1\cdot {\text{M\_WS}} + \epsilon & LM*\\
Model 2 & \text{BC\_WS} = \beta _0 + f(\text{M\_WS}) + \epsilon& \\
Model 3 & \text{BC\_WS} = \beta _0 + \beta _1\cdot W\_WS+ \beta _2\cdot \text{\text{W\_Direction}}+ \beta _3\cdot \text{Temperature} + \beta _4\cdot \text{Pressure} + \epsilon & LM*\\
Model 4 & \text{BC\_WS} = \beta _0 + f(\text{M\_WS})+ f(\text{W\_Direction})+ f(\text{Temperature}) + f(\text{Pressure}) + \epsilon &\\
Model 5 & \text{BC\_WS} =\beta _0 + \beta _1\cdot (\text{M\_WS})+ f(\text{W\_Direction})+ f(\text{Temperature}) + f(\text{Pressure}) + \epsilon &\\
Model 6 & \text{BC\_WS} = \beta _0 + \beta _1\cdot M\_U+ \beta _2\cdot \text{M\_V}+ \beta _3\cdot \text{Temperature} + \beta _4\cdot \text{Pressure} + \epsilon & LM*\\
Model 7 & \text{BC\_WS} = \beta _0 + f(M\_U)+ f(\text{M\_V})+ f(\text{Temperature}) + f(\text{Pressure}) + \epsilon&\\
\end{tblr}
\end{document}